Unmanned aerial vehicle-mounted contact type acoustic excitation and acquisition device and boiler tube wall detection method

Abstract

The invention provides an unmanned aerial vehicle-mounted contact type acoustic excitation and acquisition device and a boiler pipe wall detection method. The device comprises an unmanned aerial vehicle flight platform, an airborne control system and a contact type detection module installed at the front end of an unmanned aerial vehicle through a flexible buffer connection mechanism. The contact type detection module is integrated with an electromagnetic adsorption unit, a mechanical excitation unit and an acoustic sensing unit. During working, the electromagnetic adsorption unit temporarily adsorbs and fixes the module on a ferromagnetic boiler water wall tube bundle to form a stable detection fulcrum; then the mechanical excitation unit conducts knocking excitation on the pipe wall, and sound wave / guided wave signals are excited; and the acoustic sensing unit receives the structural vibration response of the pipe wall. The influence of hovering instability and excitation reaction force of the unmanned aerial vehicle is effectively overcome, tight acoustic coupling of the sensor and the pipe wall is ensured, and the vibration noise of the unmanned aerial vehicle is isolated, so that efficient and stable contact type acoustic detection of penetrating a surface ash deposition layer can be realized on the pipe wall of the boiler from high altitude.

Description

Technical Field

[0001] This invention relates to the field of industrial nondestructive testing technology, specifically to an unmanned aerial vehicle (UAV)-borne contact acoustic excitation and acquisition device and a boiler tube wall inspection method. More particularly, it relates to an automated inspection device that utilizes an adsorption mechanism to achieve stable high-altitude contact and acquires acoustic fingerprints of the tube wall through mechanical excitation to identify cracks and deformations. Background Technology

[0002] With the rapid development of the energy industry, the operational safety and efficiency of thermal power plants have received widespread attention. As the core equipment of a thermal power plant, the boiler's water-cooled walls and other heating surface tubes are subjected to high temperatures, high pressures, and complex flue gas environments for extended periods, making them highly susceptible to corrosion, wear, thermal fatigue cracks, and tube wall deformation. Tube bursts are one of the main causes of unplanned shutdowns of thermal power units, severely impacting the plant's economic efficiency and production safety. Therefore, regularly conducting comprehensive and accurate non-destructive testing of the boiler's heating surfaces is a necessary means to ensure the safe operation of the unit.

[0003] Currently, boiler heating surface inspection mainly relies on manual maintenance. This method typically requires erecting tall scaffolding or using lifting platforms inside the furnace, which not only involves long preparation times and high maintenance costs, but also presents a harsh working environment (high dust, dim lighting, and confined spaces), posing a significant threat to the safety of inspection personnel. Although wall-climbing robot technology has emerged in recent years, the surface of water-cooled wall tubes is uneven due to ash and coking, and there are gaps and obstacles between the tubes. This results in slow movement speed and poor obstacle-crossing ability for wall-climbing robots, making it difficult to meet the needs of large-area rapid screening.

[0004] As an emerging alternative, unmanned aerial vehicles (UAVs) are increasingly being used in industrial inspection due to their high flexibility and ability to operate without contact with obstacles. However, most existing industrial UAV inspections are limited to non-contact visual inspection (such as visible light cameras or infrared thermal imaging). While visual inspection can detect obvious external damage, it is often ineffective for internal defects such as tiny cracks covered by dust, early stress deformation, or thinning of pipe walls. Acoustic or vibration detection (such as the shock echo method) is an effective method for detecting such structural defects, but this method usually requires the excitation device to be in physical contact with the object being tested to ensure sufficient energy coupling into the pipe wall and to receive a high signal-to-noise ratio guided wave signal.

[0005] Applying contact acoustic detection technology to drones presents significant technical challenges. Firstly, there's the issue of flight stability and contact force control: drones, when hovering, are floating platforms, making it difficult to apply stable contact pressure. When onboard devices attempt to "knock" or vibrate the pipe wall, the resulting reaction force can disrupt the drone's balance, causing positional drift and even leading to a crash. Secondly, there are issues of signal coupling and noise interference: if the contact is not tight, the acoustic signal will experience significant attenuation at the air-metal interface; simultaneously, the high-frequency aerodynamic noise from the drone's rotor and fuselage vibrations will severely contaminate the weak echo signals collected by the acoustic sensors, making it difficult to extract crack features.

[0006] Therefore, there is an urgent need to develop an unmanned aerial vehicle (UAV)-borne contact detection device that can overcome hovering instability, effectively resist vibration reaction force, and achieve high-quality acoustic signal acquisition. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the purpose of this invention is to provide an unmanned aerial vehicle (UAV)-borne contact acoustic excitation and acquisition device and a boiler tube wall detection method.

[0008] According to the present invention, an unmanned aerial vehicle (UAV)-borne contact acoustic excitation and acquisition device includes: Unmanned aerial vehicle (UAV) flight platform; Airborne control systems; and The contact detection module is installed at the front end of the UAV flight platform via a flexible buffer connection mechanism; The contact detection module includes: An electromagnetic adsorption unit is used to adsorb and fix the contact detection module onto a ferromagnetic boiler water-cooled wall tube bank. A mechanical excitation unit is used to apply mechanical excitation to the tube wall in the adsorbed state to generate acoustic or guided wave signals; and An acoustic sensing unit is used to receive the vibration response signal excited by the mechanical excitation unit and propagating within the pipe wall; The airborne control system is connected to the contact detection module and is used to control the attraction and release of the electromagnetic adsorption unit, the triggering of the mechanical excitation unit, and the signal acquisition of the acoustic sensing unit.

[0009] Preferably, the electromagnetic adsorption unit includes at least one set of controllable electromagnets or magnetic chucks, and its adsorption surface is designed as a concave surface structure that conforms to the curvature of the water-cooled wall tube array.

[0010] Preferably, the contoured concave surface structure is a V-groove or a circular arc surface.

[0011] Preferably, the mechanical excitation unit is integrated at the center of the contact detection module, and uses an electromagnetic solenoid or voice coil motor as an actuator for vertically striking or vibrating the tube wall.

[0012] Preferably, the acoustic sensing unit consists of a piezoelectric sensor or a contact microphone array arranged around the mechanical excitation unit, and the sensor surface is covered with an acoustic coupling material.

[0013] Preferably, the flexible buffer connection mechanism is used to physically isolate the transmission of vibration from the UAV flight platform to the contact detection module, and allows the contact detection module to have angle adaptive capability when contacting the pipe wall.

[0014] Preferably, the airborne control system includes an airborne controller, which respectively transmits through: Flight controller interface, for communicating with the drone's flight controller; An adsorption driving circuit controls the on / off power supply of the electromagnetic adsorption unit; The excitation trigger circuit triggers the mechanical excitation unit to operate; and The signal acquisition circuit acquires and processes the signals from the acoustic sensing unit.

[0015] A boiler tube wall inspection method according to the present invention, based on the aforementioned UAV-borne contact acoustic excitation and acquisition device, includes the following steps: Step S1: Control the UAV flight platform to fly to the vicinity of the water-cooled wall tube bank to be tested, so that the contact detection module is aligned with the target tube wall; Step S2: Control the electromagnetic adsorption unit to be powered on and fix the contact detection module to the target tube wall; Step S3: Under the stable adsorption state, control the mechanical excitation unit to excite the tube wall, and simultaneously control the acoustic sensing unit to collect the vibration response signal of the tube wall; Step S4: Control the electromagnetic adsorption unit to de-energize and release, so that the contact detection module detaches from the pipe wall; Step S5: Control the UAV flight platform to move to the next detection point, and repeat steps S1 to S4.

[0016] Preferably, in step S2, the stability of the adsorption is determined by monitoring the current or contact pressure of the electromagnetic adsorption unit.

[0017] Preferably, in step S1, the UAV uses its onboard depth camera or lidar to identify the position of the water-cooled wall tube array and perform close-up positioning.

[0018] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention solves the instability problem of flight contact: This invention innovatively introduces an electromagnetic adsorption unit, utilizing a "first adsorption, then detection" operating mode to transform the floating UAV into a relatively stationary "aerial attachment point." This mechanism effectively overcomes the reaction force generated by mechanical excitation, preventing the UAV from being bounced away and ensuring the consistency of excitation force and position.

[0019] 2. This invention significantly improves acoustic signal quality: The continuous and stable contact pressure provided by magnetic adsorption ensures good acoustic coupling efficiency between the acoustic sensor and the metal pipe wall covered by dust. Simultaneously, the flexible buffer connection mechanism effectively isolates high-frequency vibration interference from the UAV rotor, greatly improving the signal-to-noise ratio of the defect signal.

[0020] 3. The present invention has the ability to detect through accumulated dust: Unlike visual detection, which is easily affected by surface dust, the mechanical excitation acoustic method of the present invention can penetrate the loose dust layer on the surface of the pipe wall, directly obtain the structural response information of the metal pipe, and effectively identify internal defects such as cracks, thinning and bulging deformation.

[0021] 4. This invention improves detection efficiency and safety: The device utilizes the mobility of drones to quickly reach any height in the furnace without the need for scaffolding, which not only reduces detection costs but also avoids the risk of personnel working in harsh environments, achieving full coverage and rapid initial screening of the boiler's heating surface. Attached Figure Description

[0022] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic diagram of the overall structure of the UAV-borne contact acoustic excitation and acquisition device in an embodiment of the present invention; Figure 2 This is a detailed structural cross-sectional view of the contact detection module in an embodiment of the present invention; Figure 3 This is a cross-sectional schematic diagram of the working state of the contact detection module and the water-cooled wall tube array adsorption in an embodiment of the present invention; Figure 4 This is a block diagram showing the electrical connection relationship between the airborne control system and each hardware unit in an embodiment of the present invention; Figure 5 This is a flowchart of the single-point automatic detection task in an embodiment of the present invention.

[0023] Explanation of reference numerals in the attached figures: The unmanned aerial vehicle (UAV) flight platform 100, flexible buffer connection mechanism 200, shell frame 300, electromagnetic adsorption unit 301, mechanical excitation unit 302, acoustic sensing unit 303, water heating surface pipe row cross section 400, and ash / coking layer 401. Detailed Implementation

[0024] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0025] This invention provides an unmanned aerial vehicle (UAV)-borne contact acoustic excitation and acquisition device for boiler tube wall inspection. It adopts an "adsorption-excitation-acquisition-release" operation mode, which ensures the flexibility of the UAV while achieving a stable contact effect similar to manual inspection on the ground, thereby efficiently and accurately acquiring acoustic fingerprint information of water-cooled walls.

[0026] like Figure 1 As shown, the present invention provides an unmanned aerial vehicle (UAV)-borne contact acoustic excitation and acquisition device for boiler tube wall inspection, which mainly consists of three core parts: UAV flight platform, flexible buffer connection mechanism and contact detection module.

[0027] Unmanned Aerial Vehicle (UAV) Flight Platform (100): As the aerial transport and mobility platform for the entire device, a quadcopter or hexacopter industrial-grade UAV is preferred, possessing sufficient payload capacity and flight stability. This platform should integrate a visual positioning system (such as a binocular depth camera) or lidar (LiDAR) to enable it to achieve centimeter-level accuracy autonomous positioning and stable hovering in environments where GPS signals are denied, such as inside a boiler furnace.

[0028] Flexible buffer connection mechanism (200): This mechanism connects the UAV fuselage (such as the belly or front) to the contact detection module. Its function is to physically isolate the high-frequency mechanical vibration generated by the UAV rotor and prevent it from being transmitted to the acoustic sensor; at the same time, it allows the detection module to have a certain degree of angle self-adaptation capability when in contact with the pipe wall.

[0029] Contact detection module: The core component of this invention, whose housing frame (300) is suspended below the UAV through the flexible buffer connection mechanism (200). This module integrates adsorption, excitation and sensing functions and directly contacts the water-cooled wall tube row to perform detection tasks.

[0030] In a preferred embodiment, the detailed structure of the contact detection module is described below. Figure 2 and Figure 3 As shown. Among them, in Figure 3 In the diagram, the ash / coke layer 401 is an irregular dotted or shaded area around the outer edge of the tube wall. This represents the ash and scale generated during boiler operation, which is an obstacle to traditional visual inspection and is what this device needs to physically penetrate. The heat-receiving surface tube bank section 400 is the large circular ring on the right side of the diagram, representing the cross-section of the water-cooled wall steel tube.

[0031] like Figure 2 As shown, the contact detection module includes a housing frame 300, and an electromagnetic adsorption unit 301, a mechanical excitation unit 302 and an acoustic sensing unit 303 mounted on the housing frame 300.

[0032] Electromagnetic adsorption unit 301 This unit is crucial for achieving stable fixation on the tube wall and consists of one or more sets of DC electromagnets symmetrically arranged on both sides of the module. To adapt to the geometry of the water-cooled wall tube bank (typically cylindrical steel tubes), the electromagnet's adsorption surface is designed as a contoured concave structure (such as a V-groove or arc surface), with a radius of curvature slightly larger than the radius of the tube wall being measured. For example... Figure 3 As shown, when the electromagnet is energized, the magnetic circuit generated closes to the ferromagnetic water-cooled wall tube, producing a strong normal attraction force (e.g., 50N-100N), which firmly "locks" the entire detection module to the tube wall, forming a temporary rigid connection point, effectively overcoming the excitation reaction force.

[0033] Mechanical excitation unit 302 This unit is located at the center of the detection module housing, specifically at the geometric center of the two electromagnetic adsorption units 301. In a preferred embodiment, a push-pull solenoid or a voice coil motor is used as the actuator. A hard rubber or metal probe is mounted at the end of the excitation head. When a trigger signal is received, the solenoid drives the probe to eject at high speed, striking the tube wall surface vertically, and then rapidly rebounding under the action of a spring. This short-duration impact generates broadband elastic waves (acoustic waves / guided waves) within the tube wall.

[0034] Acoustic sensing unit 303 This unit is used to pick up the vibration response of the pipe wall with high fidelity. In a specific implementation, a contact sensor array, such as a piezoelectric ceramic sensor (PZT) or a microelectromechanical system (MEMS) contact microphone, is used to surround the mechanical excitation unit 302.

[0035] The working surface of the sensor (the side in contact with the pipe wall) is covered with a dry coupling pad made of soft silicone or polyurethane material. Utilizing the pressure provided by the electromagnetic adsorption unit, a tight fit with the pipe wall can be achieved without liquid coupling agent. Its function is to pick up the vibration response signal excited by the excitation unit and after it propagates, reflects, and attenuates within the pipe wall.

[0036] like Figure 4 As shown, the electrical system of the device is based on an onboard microcontroller (MCU) or FPGA, and is connected to the following modules via a bus: Flight controller interface: Communicates with the UAV flight controller via UART or CAN bus, reads flight status (such as "target point reached"), and sends "hover" or "fine-tune position" commands to the UAV, realizing the coordination between the payload and the flight platform.

[0037] Adsorption drive circuit: includes MOSFET switches or relays to control the power supply to and from the electromagnetic adsorption unit, and has a current monitoring function to determine whether the adsorption is secure (e.g., a sudden change in current indicates that the magnetic circuit is closed).

[0038] Excitation trigger circuit: used to generate high-voltage pulses to drive the mechanical excitation unit and precisely control the striking force (pulse width) and frequency (pulse interval).

[0039] Signal acquisition circuit: Includes signal conditioning (filtering, amplification) and high-speed analog-to-digital converter (ADC) for high-fidelity acquisition of analog signals from acoustic sensing units, and stores the digitized waveform data to the onboard SD card or transmits it back via wireless link.

[0040] The specific steps for the device of the present invention to perform single-point detection are as follows: Step S1: Approximation Positioning The drone flies to the water-cooled wall area of ​​the boiler to be inspected. The onboard controller automatically identifies the position of the water-cooled wall tube bank based on preset detection point coordinates or through image recognition (using an onboard depth camera). The controller guides the drone to adjust its attitude so that the contact detection module under the fuselage is aligned with the predetermined detection point on the target tube wall. Subsequently, the drone slowly approaches the tube wall horizontally at a low speed (e.g., 0.1 m / s).

[0041] Step S2: Contact and Adsorption When the distance sensor (such as infrared ranging) at the front end of the detection module detects a distance less than a preset threshold (such as 2cm), the airborne controller immediately activates the adsorption drive circuit to power the electromagnetic adsorption unit (301). As the UAV moves forward slightly, the adsorption surface contacts the tube wall, and the magnetic force instantly pulls the module toward the tube wall and locks it in place.

[0042] At this point, the drone flight control enters the "attitude hold" mode, allowing the flexible buffer mechanism to deform, keeping the main body of the drone hovering in the air, while the detection module remains stationary relative to the pipe wall.

[0043] Step S3: Stimulation and Acquisition After confirming stable adsorption (by monitoring the electromagnet current or contact pressure sensor), the control system triggers the mechanical excitation unit to strike the tube wall once or multiple times. Simultaneously, the acoustic sensing unit synchronously acquires the ring-down signal of the tube wall's vibration.

[0044] Data processing logic: The acquired signal contains modal information of the pipe wall. If there are cracks or severe thinning of the pipe wall, its natural frequency will shift, and the signal attenuation rate (damping) will increase significantly.

[0045] Step S4: Release and Evacuation After data acquisition is complete, the control system disconnects the power supply to the electromagnetic adsorption unit, and the magnetic force disappears. The drone then performs a backward flight maneuver, using the pulling force to detach the detection module from the pipe wall.

[0046] Step S5: Displacement Reset The drone moves vertically or horizontally along the water-cooled wall pipe array to the next detection point, repeating steps S1 to S4.

[0047] Through the above-described embodiments, the present invention cleverly solves the problem of "lack of mechanical fulcrum" in UAV aerial operations by utilizing the electromagnetic adsorption mechanism, making high-precision contact acoustic detection possible. It can effectively penetrate the ash / coke layer 401 on the surface of the heated surface and identify deep cracks and deformation defects.

[0048] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0049] Specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the essence of the present invention. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. A UAV-borne contact acoustic excitation and acquisition device, characterized in that, include: Unmanned aerial vehicle (UAV) flight platform (100); Airborne control system; as well as The contact detection module is installed at the front end of the UAV flight platform (100) via a flexible buffer connection mechanism (200); The contact detection module includes: An electromagnetic adsorption unit (301) is used to adsorb and fix the contact detection module onto a ferromagnetic boiler water-cooled wall tube bank. Mechanical excitation unit (302) is used to apply mechanical excitation to the tube wall in the adsorbed state to generate acoustic waves or guided wave signals; and An acoustic sensing unit (303) is used to receive the vibration response signal excited by the mechanical excitation unit (302) and propagating within the pipe wall; The airborne control system is connected to the contact detection module and is used to control the attraction and release of the electromagnetic adsorption unit (301), control the triggering of the mechanical excitation unit (302), and control the acoustic sensing unit (303) to collect signals.

2. The UAV-borne contact acoustic excitation and acquisition device according to claim 1, characterized in that, The electromagnetic adsorption unit (301) includes at least one set of controllable electromagnets or magnetic chucks, and its adsorption surface is designed as a contoured concave structure adapted to the curvature of the water-cooled wall tube array.

3. The UAV-borne contact acoustic excitation and acquisition device according to claim 2, characterized in that, The contoured concave structure is a V-groove or a circular arc surface.

4. The UAV-borne contact acoustic excitation and acquisition device according to claim 1, characterized in that, The mechanical excitation unit (302) is integrated at the center of the contact detection module and uses an electromagnetic solenoid or voice coil motor as an actuator to vertically strike or vibrate the tube wall.

5. The UAV-borne contact acoustic excitation and acquisition device according to claim 1, characterized in that, The acoustic sensing unit (303) consists of a piezoelectric sensor or a contact microphone array arranged around the mechanical excitation unit (302), and the sensor surface is covered with an acoustic coupling material.

6. The UAV-borne contact acoustic excitation and acquisition device according to claim 1, characterized in that, The flexible buffer connection mechanism (200) is used to physically isolate the transmission of vibration of the UAV flight platform (100) to the contact detection module and to allow the contact detection module to have angle adaptive capability when in contact with the pipe wall.

7. The UAV-borne contact acoustic excitation and acquisition device according to claim 1, characterized in that, The airborne control system includes an airborne controller, which respectively transmits through: Flight controller interface, for communicating with the drone's flight controller; The adsorption driving circuit controls the power supply to and from the electromagnetic adsorption unit (301); The excitation triggering circuit triggers the mechanical excitation unit (302) to operate; as well as The signal acquisition circuit acquires and processes the signals from the acoustic sensing unit (303).

8. A method for detecting boiler tube walls, based on the UAV-borne contact acoustic excitation and acquisition device according to any one of claims 1 to 7, characterized in that, Includes the following steps: Step S1: Control the UAV flight platform (100) to fly to the vicinity of the water-cooled wall tube bank to be tested, so that the contact detection module is aligned with the target tube wall; Step S2: Control the electromagnetic adsorption unit (301) to be powered on and fix the contact detection module to the target tube wall; Step S3: Under the adsorption stable state, control the mechanical excitation unit (302) to excite the tube wall, and simultaneously control the acoustic sensing unit (303) to collect the vibration response signal of the tube wall; Step S4: Control the electromagnetic adsorption unit (301) to de-energize and release, so that the contact detection module is detached from the tube wall; Step S5: Control the UAV flight platform (100) to move to the next detection point, and repeat steps S1 to S4.

9. The boiler tube wall inspection method according to claim 8, characterized in that, In step S2, the stability of the adsorption is determined by monitoring the current or contact pressure of the electromagnetic adsorption unit (301).

10. The boiler tube wall inspection method according to claim 8, characterized in that, In step S1, the UAV uses its onboard depth camera or lidar to identify the location of the water-cooled wall tube array and perform close-up positioning.

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